Active Power Oscillation and Suppression Techniques between Two Parallel Synchronverters during Load Fluctuations

Active power oscillation is observed when two or more parallel synchronverters undergo load fluctuations, potentially impacting the safe operation of the synchronverters. This article provides a fundamental analysis for the power oscillation mechanisms and proposes a new control strategy for suppressing power oscillation especially the oscillation excitation is proposed. It is found that power oscillation is inherently caused by weak damping and large inertia of the synchronverters under the condition of undesirable instantaneous active power sharing. Then, the condition for reducing the oscillation excitation of synchronverters, which is caused by undesirable instantaneous active power sharing, is deduced. The new control strategy effectively suppresses the power oscillation by adding a virtual damping element for enhancing the system damping and a virtual reactance for reducing the oscillation excitation to the conventional control scheme without changing the basic dynamic and steady characteristics of the synchronverters. The theoretical analysis and the proposed oscillation suppression control techniques are validated with an extensive hardware-in-loop simulation study.